Nanometer scale data storage device and associated positioning system

ABSTRACT

A data storage system that includes a positioning system for positioning the write/read mechanism and the storage medium of the data storage device with respect to each other in first and second predefined directions. The positioning system comprises a positioning apparatus comprising microfabricated first and second positioning assemblies. The positioning system further comprises a controller to position a positionable support structure of the first positioning assembly in a first predefined direction within a range of positioning that is larger than the range of movement of a moveable support structure of the first positioning assembly by controlling (A) a stationary support structure clamp in clamping and unclamping the positionable structure to and from the support structure, (B) a moveable structure clamp in clamping and unclamping the positionable support structure to and from the moveable support structure, and (C) the movement of the moveable support structure.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/630,350, filed Jul. 29, 2003, which is a continuation of U.S. patentapplication Ser. No. 08/955,031, filed Oct.21, 1997, now U.S. Pat. No.6,724,712, which is a division of U.S. patent application Ser. No.08/506,516, filed Jul. 24, 1995, now U.S. Pat. No. 5,751,683.

FIELD OF THE INVENTION

The present invention relates generally to data storage devices andtheir associated positioning systems. In particular, it relates to datastorage devices to store and recover data by producing optical,electrical, or mechanical changes in storage media at nanometer level(i.e., scale) increments (i.e., intervals) with microfabricatedstructures which are positionable at nanometer level increments with thepositioning system of the data storage devices.

BACKGROUND OF THE INVENTION

UV erasable programmable read only memories (UVPROMs) are well known tothose skilled in the art. These types of memories comprise distinctcharge storage cells or sites and include a separate read/write line toeach of the charge storage cells. In order to write data to the UVPROM,it is first bulk erased by exposing simultaneously all of the chargestorage cells to UV light or radiation to leak off any charges stored bythem. Then, data is written to selected charge storage cells byinjecting charges in them with the corresponding read/write lines. Thesecharges may then be detected with the read/write lines so as to readdata from the charge storage cells. Since UVPROMs include separateread/write lines to the charge storage cells, the charge storage cellsare not able to be spaced apart at nanometer level increments so thatthe overall size of the UVPROM could be reduced. However, a UVPROM typestructure with charge storage cells at nanometer level increments couldbe used if a mechanism were developed that could (1) selectively andindividually write data to each charge storage cell by leaking off acharge in the charge storage cell with UV light, and (2) electricallyread data from each storage cell by detecting or sampling a charge inthe charge storage cell without a read line to the charge storage cell.

Moreover, recently attempts have been made at providing data storagedevices where data can be electrically or mechanically written to andelectrically read from a storage medium at nanometer level increments.However, these data storage devices all suffer from significantproblems.

For example, U.S. Pat. No. 5,317,533, describes a data storage deviceutilizing scanning tunneling microscope (STM) probes to read and writedata to a storage medium by producing and measuring tunneling currentsbetween the STM probes and the storage medium. Furthermore, U.S. Pat.No. 5,289,408 describes a similar data storage device with apiezoelectric positioning apparatus for positioning STM probes over thestorage medium to read and write data to the storage medium. Thispositioning apparatus is bulky and impractical to use as a part of adata storage device in a computing system. Moreover, since positioningof the STM probes over the storage medium in the X and Y directions islimited to the range of movement of the X and Y piezoelectric translatorelements of the positioning apparatus, the storage capacity of this datastorage device is also limited by this range of movement. And, toincrease this range of movement so that the storage capacity of the datastorage device is increased, the size of the X and Y piezoelectrictranslator elements must also be increased. This unfortunately increasesthe overall size, read/write times, weight, and power requirements ofthe data storage device.

Furthermore, U.S. Pat. No. 5,038,322 describes still another datastorage device that utilizes STM probes. In this storage device, the STMprobes are used to deform a deformable storage medium to write data toit which is represented by the deformations. Then, by producing andmeasuring a tunneling current between the STM probes and the storagemedium, the deformations can be identified so as to read from thestorage medium the data that was written to it. However, the STM probescomprise a soft conductive material, such as conductive silicon,tungsten, aluminum, or gold which wears down after prolonged use indeforming the storage medium. Thus, the useful life of this type of datastorage device is limited.

BRIEF SUMMARY OF THE INVENTION

The foregoing problems are solved by a data storage system that includesa positioning system for positioning the write/read mechanism and thestorage medium of the data storage device with respect to each other infirst and second predefined directions. The positioning system comprisesa positioning apparatus comprising microfabricated first and secondpositioning assemblies.

The first positioning assembly includes a stationary support structure,a moveable support structure, a positionable support structure, astationary support structure clamp, and a movable support structureclamp. The movable support structure is movably coupled to thestationary support structure and is moveable within a range of movementin a first predefined direction with respect to the stationary supportstructure. The positioning system further comprises a controller toposition the positionable support structure in the first predefineddirection within a range of positioning that is larger than the range ofmovement of the moveable support structure. It does so by controlling(A) the stationary support structure clamp in clamping and unclampingthe positionable structure to and from the support structure, (B) themoveable structure clamp in clamping and unclamping the positionablesupport structure to and from the moveable support structure, and (C)the movement of the moveable support structure.

In one embodiment, the second positioning assembly comprises astationary support structure and a moveable support structure. Themovable support structure is movably coupled to the stationary supportstructure and is moveable within a range of movement in a secondpredefined direction with respect to the stationary support structure.The controller controls the positioning of the moveable structure in thesecond direction within the range of movement of the moveable structure.In another embodiment, the second positioning assembly may beconstructed and controlled in the same way as the first positioningassembly.

In one embodiment, one of the write/read mechanism and the storagemedium is carried by the positionable support structure so that it ispositioned with the first positioning assembly. The other one of thewrite/read mechanism and the storage medium is positioned with thesecond positioning assembly. In another embodiment, the positionablesupport structure carries the second positioning assembly and one of thewrite/read mechanism and the storage medium is positioned with thesecond positioning assembly while the other is held stationary.

In one embodiment, the storage medium is deformable and the write/readmechanism comprises one or more write probes and one or more readprobes. The write probes each include a write tip with a highly obduratecoating capable of deforming the storage medium and a write tippositioning apparatus to lower the write tip. The read probes eachinclude a conductive read tip. The controller is used to (A) during awrite mode, control the first and second positioning apparatus inpositioning the write probes over the storage medium, (B) during thewrite mode, control each write tip positioning apparatus in lowering thecorresponding write tip a predetermined amount into the storage mediumso as to cause a predetermined amount of deformation in the storagemedium representing data written thereto, (C) during a read mode,control the first and second positioning apparatus in positioning theread probes over the storage medium, and (D) during the read mode,produce and measure a tunneling current between each conductive read tipand the storage medium to identify a predetermined amount of deformationcaused in the storage medium during the write mode so that the datawritten thereto is read therefrom.

In another embodiment, the data storage device comprises one or moreprobes each comprising a tip with a conductive highly obdurate coatingcapable of deforming the storage medium and a tip positioning apparatusto lower the tip. The controller in this embodiment is used to (A)during a write mode, control the probe and storage medium positioningapparatus in positioning the probes over the storage medium, (B) duringthe write mode, control each tip positioning apparatus in lowering thecorresponding tip a predetermined amount into the storage medium so asto cause a predetermined amount of deformation in the storage mediumrepresenting data written thereto, (C) during a read mode, control theprobe and storage medium positioning apparatus in positioning the probesover the storage medium, (D) during the read mode, control each tippositioning apparatus in lowering the corresponding tip close to thestorage medium, and (E) during the read mode, produce and measure atunneling current between the conductive obdurate coating of each tipand the storage medium to identify a predetermined amount of deformationcaused in the storage medium during the write mode so that the datawritten thereto is read therefrom.

In still another embodiment, the data storage device comprises a storagemedium alterable by light, one or more light emitting write probes eachcapable of emitting light, and one or more read probes each capable ofdetecting alterations of the storage medium caused by light. Thecontroller is used in this embodiment to (A) during a write mode,control the positioning apparatus in positioning the write probes overthe storage medium so that the light emitting write tips are over thestorage medium, (B) during the write mode, control each light emittingwrite probe to emit a predetermined amount of light so as to cause apredetermined amount of alteration of the storage medium so as to writedata thereto, (C) during read modes, control the positioning apparatusin positioning the read probes over the storage medium so that each readprobe detects a predetermined amount of alteration of the storage mediumcaused during the write mode, and (D) during the read mode, measure eachdetected predetermined amount of alteration of the storage medium sothat the data written to the storage medium during the write mode isread therefrom.

In yet another embodiment, the data storage device comprises anelectrically alterable storage medium, a triangular ridge supportstructure, one or more conductive triangular ridges on the basestructure, and an acoustic wave generator on one of the triangular ridgesupport structure and the storage medium to produce surface acousticwaves thereon that propagate in a direction parallel to the axial lengthof the triangular ridges. The controller in this embodiment is used to(A) during a write mode, control the positioning apparatus inpositioning the triangular ridge support structure over the storagemedium so that each triangular ridge is over a corresponding region ofthe storage medium to be written, (B) during the write mode, control theacoustic wave generator to produce an acoustic wave, (C) during thewrite mode, apply at a predetermined time across each triangular ridgeand the storage medium a voltage pulse having a predetermined voltageand duration while the acoustic wave produced during the write modepropagates so that a portion of the triangular ridge above thecorresponding region to be written is displaced down theretoward and thecorresponding region to be written is electrically altered by apredetermined amount, (D) during a read mode, control the positioningapparatus in positioning the triangular ridge support structure over thestorage medium so that each triangular ridge is over a correspondingregion of the storage medium to be read, (E) during the read mode,control the acoustic wave generator to produce an acoustic wave, (F)during the read mode, with each triangular ridge at a predetermined timewhile the acoustic wave produced during the read mode propagates so thata portion of the triangular ridge above the corresponding region to beread is displaced down theretoward, detect a predetermined amount ofelectrical alteration of the corresponding region to be read causedduring the write mode, (G) during the read mode, measure each detectedpredetermined amount of electrical alteration of the correspondingregion to be read so that the data written thereto during the write modeis read therefrom.

In still yet another embodiment, the positioning system is used in abiochemical instrument. The biochemical instrument comprises a probethat includes a porous tip and a tip positioning apparatus to positionthe tip with respect to a sample material. The positioning apparatus isused to position the probe and sample material with respect to eachother. The controller is used to (A) control the positioning apparatusin positioning the probe over the sample, and (B) control the tippositioning apparatus in lowering the tip into the sample material toproduce a biochemical interaction between the porous tip and the samplematerial.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a positioning system in accordance with the presentinvention.

FIG. 2 shows another embodiment of the positioning system of FIG. 1.

FIG. 3 shows yet another embodiment of the positioning system of FIG. 1.

FIG. 4 shows a cross sectional side view of the positioning system ofFIG. 1 along the line 4-4.

FIG. 5 shows a cross sectional side view of the positioning system ofFIG. 1 along the line 5-5.

FIG. 6 shows a cross sectional side view of the positioning system ofFIG. 1 along the line 6-6.

FIG. 7 shows a cross sectional side view of the positioning system ofFIG. 1 along the line 7-7.

FIG. 8 shows the positionable support structure of the positioningsystem of FIG. 1.

FIG. 9 shows a data storage device in accordance with the inventionwhich includes the positioning system of FIG. 1.

FIG. 10 shows a write probe capable of being used in the data storagedevice of FIG. 9.

FIG. 11 shows another embodiment of the tip positioning apparatus of theprobes of FIGS. 10, 12.

FIG. 12 shows a read probe capable of being used in the data storagedevice of FIG. 9.

FIG. 13 shows a side cross sectional view of a storage medium capable ofbeing used in the data storage device of FIG. 9.

FIG. 14 shows top cross sectional view of the storage medium of FIG. 13.

FIG. 15 shows another storage medium capable of being used in the datastorage device of FIG. 9.

FIG. 16 shows a side cross sectional view of the storage medium of FIG.15.

FIG. 17 shows another write probe capable of being used in the datastorage device of FIG. 9.

FIG. 18 shows still another write probe capable of being used in thedata storage device of FIG. 9.

FIG. 19 shows another embodiment of the read/write mechanism of FIG. 9.

FIG. 20 provides another view of the read/write mechanism of FIG. 19.

FIG. 21 shows another embodiment of the read/write mechanism of FIG. 19.

FIG. 22 shows a top view of the read/write mechanism of FIG. 21.

DETAILED DESCRIPTION OF THE INVENTION

The present invention primarily concerns various types of data storagesystems. These data storage systems are related by their positioningsystems, storage mediums, and/or read/write mechanisms.

Positioning System

Referring to FIG. 1, there is shown a positioning system 100 forpositioning objects at nanometer level or scale increments. As will bemore evident from the following discussions, the positioning system maybe used as the positioning system in the data storage devices describedherein or as the positioning system in measuring systems (such as atomicforce microscopes (AFMs), scanning tunneling microscopes (STMs), opticalmicroscopes, and near-field microscopes), microfabrication systems, orother instruments that require precise positioning.

Positioning system 100 includes a programmed controller 102 and amicrofabricated XY translator or positioning apparatus comprising an Xtranslator assembly 104 to move an object in the X direction and a Ytranslator assembly 106 to move an object in the Y direction. Whenassembled, the X and Y translator assemblies are mounted together withmounting pedestals or bumps 108 and 110. The assembled X and Ytranslator assemblies are sealed airtight in a vacuum or are evacuatedas a final assembly step. Operation in a vacuum substantially improvesthe operational speed of all mechanical elements of the positioningsystem and also inhibits the formation of oxides on these elements.Alternatively, the positioning system may be assembled in and filledwith an inert gas, such as argon, at or near atmospheric pressure.

X translator assembly 104 may be formed of a semiconductive material,such as silicon, and comprises a stationary support structure and amoveable support structure movably coupled to the stationary supportstructure. The stationary support structure comprises a stationarysupport structure base 112 and a pair of stationary support structurerails or bars 114. The stationary support structure base and rails areintegrally connected together. The moveable support structure comprisesa moveable support structure base 118 and a pair of moveable supportstructure rails 120. The moveable support structure base and rails areintegrally connected together.

Furthermore, referring to FIGS. 1 and 4, mounting pedestals 108 and 110are integrally connected to stationary support structure base 112.Spring connectors 124 are integrally connected to mounting pedestals 108and are integrally connected to one end of moveable support structurebase 118 and physically suspend this end over the stationary supportstructure base. Moreover, the spring connectors act as springs. Thus,the moveable support structure is physically movably coupled to thestationary support structure by mounting pedestals 108 and springconnectors 124.

Referring back to FIG. 1, to move or drive the moveable supportstructure, X translator assembly 104 also includes an electrostatic combdrive or actuator comprising a stationary comb structure 128 and amoveable comb structure 130. The stationary comb structure is integrallyconnected to stationary support structure base 112. The moveable combstructure is integrally connected to moveable support structure base118.

The electrostatic comb drive is of the type and operates in the mannerdescribed in “Electrostatic Comb Drive for Resonant Sensor and ActuatorApplications”, University of California at Berkeley DoctoralDissertation, by William Chi-Keung Tang Nov. 21, 1990, which is herebyexplicitly incorporated by reference. Specifically, the comb fingers ofmoveable comb structure 130 are aligned between the comb fingers ofstationary comb structure 128. And, referring to FIGS. 1 and 4, thestationary and moveable comb structures are made to be conductive sothat when a differential voltage is applied across them, their combfingers interact electrostatically with each other and the moveable combstructure is electrostatically suspended over stationary supportstructure base 112 and moves with respect to the stationary combstructure in the X direction. Thus, since one end of moveable supportstructure base 118 is integrally connected to the moveable combstructure, the moveable support structure is electrostatically movablycoupled to the stationary support structure and is moveable in the Xdirection.

Turning again to FIG. 1, in order to control the electrostatic combdrive described above, positioning system 100 includes controller 102.The controller is electrically coupled to stationary and moveable combstructures 128 and 130 and provides a differential voltage across them.By controlling the level of the differential voltage, the controller cancontrol movement of or drive the moveable support structure back andforth in the X direction over the stationary support structure with theelectrostatic comb drive. For example, when a suitably largedifferential voltage is applied, the moveable support structure movestoward the mounting pedestals 108 and forces spring connectors 124 to bedeflected to a position different then their normal undeflectedposition. Then, when no or a suitably small differential voltage isapplied, the spring connectors return to their normal undeflectedposition and force the moveable support structure back to or to beretracted to its original position.

Moreover, controller 102 can control movement of the moveable supportstructure in nanometer level increments (e.g., 10 nanometer increments).In other words, the controller can control positioning of the moveablesupport structure at the nanometer level. However, as is evident fromthe foregoing, the moveable support structure has only a limited rangeof movement in the X direction at the micrometer level (e.g., 35 to 45micrometers).

In an alternative embodiment, a second electrostatic comb drive replacesmounting pedestals 108 and spring connectors 124 to electrostaticallymove and suspend one end of the moveable support structure base 118.Thus, in this case, the second electrostatic comb drive is usedsimilarly to and in conjunction with the earlier described electrostaticcomb drive to electrostatically movably couple the moveable supportstructure to the stationary support structure.

In another embodiment, as shown in FIG. 2, the electrostatic comb driveof X translator assembly 104 is replaced by a heater drive comprising athermally expandable and contractible structure 132 and heater elements134 on the thermally expandable and contractible structure. One end ofthe thermally expandable and contractible structure is integrallyconnected to stationary support structure base 112. The other end of thethermally expandable and contractible structure is integrally connectedto moveable support structure base 118 and suspends over the stationarysupport structure base the end of the moveable support structure basecoupled to it. The heater elements are used to selectively heat thethermally expandable and contractible structure so that it thermallyexpands and contracts and moves back and forth in the X direction. Thus,since one end of the moveable support structure base is integrallyconnected to the thermally expandable and contractible structure, themoveable support structure is physically movably coupled to thestationary support structure by the thermally expandable andcontractible structure and is moveable back and forth in the Xdirection.

Furthermore, in this embodiment, to control the heater drive justdescribed, controller 102 is electrically coupled to heater elements 134and thermally expandable and contractible structure 132 to provide acurrent that flows through the heater elements. By controlling theamount of current that flows through the heater elements, the controllercan control positioning of the moveable support structure in nanometerlevel increments in the X direction in a similar manner to thatdescribed earlier for the embodiment of FIG. 1.

In another embodiment shown in FIG. 3, a piezoelectric drive formed by apiezoelectric structure 136 and electrodes 138 fixed to thepiezoelectric structure (with the electrode on the underside of thepiezoelectric structure not being shown) is used to control movement ofthe moveable support structure of X translator assembly 104. Thepiezoelectric structure may comprise silicon dioxide such that one endof the piezoelectric structure is integrally connected to moveablesupport structure base 118 and suspends over stationary supportstructure base 112 the end of the moveable support structure basecoupled to it. The other end of the piezoelectric structure isintegrally connected to a stationary suspension structure 139 which isitself integrally connected to the stationary support structure base andsuspends the piezoelectric structure over the stationary supportstructure base. The electrodes are used to selectively apply a voltageto the piezoelectric structure to expand and contract it so that itmoves back and forth in the X direction. Thus, since one end of themoveable support structure base is connected to the piezoelectricstructure, the moveable support structure is physically movably coupledto the stationary support structure by the piezoelectric structure andis moveable in the X direction.

To control the piezoelectric drive just described, controller 102 iselectrically coupled to electrodes 138 so that it can provide a voltageacross the electrodes which is applied to piezoelectric structure 136 bythe electrodes. The controller can control positioning of the moveablesupport structure in nanometer level increments back in the X directionover the stationary support structure in a similar manner to thatdescribed earlier for the embodiment of FIG. 1. It does so bycontrolling the level of voltage applied to the piezoelectric structure.

Furthermore, turning again to FIG. 1, the stationary support structureincludes stationary support structure rails 114 and the moveable supportstructure includes moveable support structure rails 120, as alluded toearlier. As shown in FIG. 5, each of the stationary support structurerails have ends integrally connected to stationary support structurebase 112 and have rail portions that are spaced from the stationarysupport structure base. In addition, referring to FIG. 4, the moveablesupport structure rails each have ends integrally connected to moveablesupport structure base 118 and have rail portions that are spaced fromthe moveable support structure base.

Referring back to FIG. 1, X translator assembly 104 further includes apositionable support structure 140 which carries an object to be movedin the X direction. The X translator assembly also includes a moveablesupport structure rail clamp and a stationary support structure railclamp to help position the positionable support structure and the objectit carries at the nanometer level in the X direction over a range ofpositioning that is greater than the range of movement of the moveablesupport structure.

As shown in FIGS. 6-8, the moveable support structure rail clampcomprises clamping bar extensions or fingers 142, clamping bars 144,push arms 146, and heater elements 160. The stationary support structurerail clamp comprises clamping bar extensions 148, clamping bars 150,push arms 152, and heater elements 162.

Referring to FIGS. 6 and 7, clamping bar extensions 142 are integrallyconnected to positionable support structure 140 and extend over moveablesupport structure rails 120 and bend down toward moveable supportstructure base 118. Similarly, clamping bar extensions 148 areintegrally connected to the positionable support structure and extendover stationary support structure rails 114 and bend down towardstationary support structure base 112.

The curved shape of clamping bar extensions 142 and 148 is due toseveral factors. First, referring to FIG. 8, the underside ofpositionable support structure 140 includes conductive interconnects orlines 154, 156, and 158. These interconnects may comprise tungsten andare patterned on and throughout the positionable support structureincluding on the undersides of the clamping bar extensions. The tensileforce of the interconnects on the undersides of the clamping barextensions helps produce their curved shape. Second, referring back toFIGS. 6 and 7, during fabrication, the clamping bar extensions are dopedwith phosphorous which also helps in producing their curved shape.

Still referring to FIGS. 6 and 7, clamping bars 144 and 150 respectivelybend in toward moveable and stationary support structure rails 120 and114 because they are respectively integrally connected to curve shapedclamping bar extensions 142 and 148. Furthermore, when push arms 146 and152 are in their natural positions, clamping bars 144 and 150respectively bend in an engage moveable and stationary support structurerails 120 and 114. This is due to the fact that, in their naturalposition, push arms 146 and 152 do not extend out far enough in the Ydirection to respectively engage clamping bars 144 and 150. As a result,under these conditions, positionable support structure 140 is clampedand coupled to the moveable and stationary support structure rails.

Moveable and stationary support structure rails 120 and 114 are made tobe conductive. Referring to FIG. 8, therefore, when the moveable supportstructure clamp clamps positionable support structure 140 to themoveable support structure rails, the moveable support structure railsare respectively electrically coupled to interconnects 154 and 156.Similarly, when the positionable support structure is clamped to thestationary support structure rails by the stationary support structureclamp, the stationary support structure rails are respectivelyelectrically coupled to interconnects 156 and 158.

Furthermore, positionable support structure 140 and push arms 146 and152 are made to be conductive or semiconductive and are electricallycoupled to interconnect 156. And, interconnect 154 is electricallycoupled to heater elements 160 located on stationary support structurerail clamping push arms 148. Moreover, interconnect 158 is electricallycoupled to heater elements 162 located on moveable support structurerail clamping push arms 142.

Therefore, when positionable support structure 140 is clamped tostationary support structure rails 114, and no or a suitably smalldifferential voltage is applied across them, no current flows throughinterconnect 154, heater elements 160, and interconnect 156. As aresult, push arms 146 remain in their normal positions because heaterelements 160 are not activated. However, when a suitably largedifferential voltage is applied across the stationary support structurerails, current does flow through interconnect 154, heater elements 160,and interconnect 156. Since heater elements 160 are located on push arms142 at locations opposite the notches of the push arms, they heat thepush arms so that they bend in at their notches and extend out in the Ydirection away from positionable support structure 140. As a result, thepush arms engage moveable support structure rail clamping bars 144 andpush these clamping bars away from the moveable support structure railsso that the clamping bars are disengaged from the moveable supportstructure rails. Thus, the positionable support structure is unclampedand uncoupled from (i.e., released from being clamped to) the moveablesupport structure rails.

Similarly, push arms 152 remain in their normal positions whenpositionable support structure 140 is clamped to moveable supportstructure rails 120 and no or a suitably small differential voltage isapplied across them. This is due to the fact that heater elements 162are not activated in this case since no current flows throughinterconnect 158, heater elements 162, and interconnect 156. However,when a suitably large differential voltage is applied across themoveable support structure rails, current does flow through interconnect158, heater elements 162, and interconnect 156. Since heater elements162 are located on the moveable support structure clamping rail pusharms at the notches of these push arms, they heat these push arms sothat they bend out at their notches and extend out in the Y directionaway from positionable support structure 140. As a result, they engagestationary support structure rail clamping bars 150 and push theseclamping bars away from the stationary support structure rails so thatthese clamping bars are disengaged from the stationary support structurerails. Thus, the positionable support structure is unclamped anduncoupled from the stationary support structure rails.

Referring back to FIG. 1, controller 102 is electrically coupled to themoveable and stationary support structure rails 120 and 140 to provideappropriate differential voltages across the moveable support structurerails and across the stationary support structure rails so as to producethe clamping and unclamping functions of the moveable and stationarysupport structure rail clamps just described. In other words, bycontrolling the level of the differential voltage, the controller cancontrol the clamping and unclamping of the positionable supportstructure to and from the moveable and stationary support structurerails.

Controller 112, the electrostatic comb, heater, and piezoelectric drivesdescribed earlier, the moveable support structure, the stationarysupport structure, and the moveable and stationary support structurerail clamps just described work cooperatively together to provide ameans to position positionable support structure 140 and the object itcarries at the nanometer level in the X direction over a range ofpositioning that is greater then the range of movement of the moveablesupport structure. To do this, the controller initially applies asuitably large differential voltage across moveable support structurerails 120 to unclamp the positionable support structure from stationarysupport structure rails 114 and no or a suitably small differentialvoltage across stationary support structure rails 120 to keep thepositionable support structure clamped to the moveable support structurerails. Then, the controller applies a suitable differential voltageacross stationary and moveable comb structures 128 and 130 to move themoveable support structure in the X direction. Since the positionablesupport structure is clamped to the moveable support structure rails,the positionable support structure and the object it carries are bothcarried by the moveable support structure. As alluded to earlier, thismay be done in nanometer level increments for positioning of thepositionable support structure and the object it carries at thenanometer level.

Then, when the maximum distance (i.e., range of movement) of themoveable comb structure in the X direction has been reached, controller112 applies no or a suitably small differential voltage across moveablesupport structure rails 120 to clamp positionable support structure 140to the stationary support structure rails and a suitably largedifferential voltage across stationary support structure rails tounclamp the positionable support structure from the moveable supportstructure rails. The controller then applies a suitable differentialvoltage across stationary and moveable comb structures 128 and 130 toreposition or retract the moveable support structure in the X directionso that it can again move the maximum distance in the X direction. Theprocess just described is then repeated until the positionable supportstructure and the object it carries have been positioned at the desiredpoint in the X direction. Thus, the positionable support structure andthe object it carries can be positioned anywhere along the length of therail portions of the stationary support structure rails. Since the railportions of the stationary support structure rails may have lengths inthe millimeter range, the range of positioning of the positionablesupport structure and the object it carries will in this case be at themillimeter level or scale and will be greater than the range of movementof the moveable support structure.

Furthermore, as alluded to earlier and shown in FIG. 1, positioningsystem 100 also includes a Y translator assembly 106. The Y translatorassembly may be comprised of a semiconductive material, such as silicon,and includes a stationary support structure 164, a moveable supportstructure 166, a pair of pedestals 168, and a pair of spring connectors170. These components respectively correspond to stationary supportstructure base 112, moveable support structure base 118, pedestals 108,and spring connectors 124 of X translator assembly 104 and areconstructed and operate similarly.

Additionally, Y translator assembly 106 also includes an electrostaticcomb drive comprising a stationary comb structure 172 and a moveablecomb structure 174. The stationary and moveable comb structuresrespectively correspond to stationary comb structure 128 and moveablecomb structure 130 of X translator assembly 104 and are constructed andoperate similarly. Controller 102 is coupled to the electrostatic combdrive of the Y translator assembly in the same manner as it is coupledto the electrostatic comb drive of the X translator assembly. As aresult, it can control positioning of moveable support structure 166 andthe object it carries in the Y direction in a similar manner as wasdescribed earlier for the moveable support structure of the X directionmovement assembly of FIG. 1.

In alternative embodiments, the electrostatic comb drive may be replacedby a heater drive or a piezoelectric drive. These heater andpiezoelectric drives would operate and be constructed similarly to theheater drive and piezoelectric drives of FIGS. 2 and 3 and be controlledby controller 102 in the same way as was described earlier.

In another alternative embodiment, Y translator assembly 106 could bemounted to or integrally connected to positionable support structure 140of X translator assembly 104. In this case, in positioning two objectsrelative to each other, one of the objects would be kept stationary andthe other object would be carried by moveable support structure 166 ofthe Y translator assembly. Furthermore, in still another alternativeembodiment, Y translator assembly 106 would be replaced by another Ytranslator assembly that is constructed similar to X translator assembly104.

MECHANICAL WRITE/ELECTRICAL READ EMBODIMENT

Referring to FIG. 9, there is shown a data storage device 200 thatincludes the XY translator apparatus and controller 102 of positioningsystem 100 described earlier. In addition, it includes a storage medium202 and a read/write mechanism comprising one or more write probes 204and one or more read probes 206. Controller 102 is used in the datastorage device not only to control the XY translator apparatus inpositioning the read and write probes and the storage medium withrespect to each other in the X and Y directions, but also in controllingmechanical writing of data to and electrical reading of data from thestorage medium by the write and read probes.

Storage medium 202 is carried by positionable support structure 140 of Xtranslator assembly 104. Write and read probes 204 and 206 are carriedby moveable support structure 166 of Y translator assembly 106.Alternatively, the storage medium may be carried by the moveable supportstructure of the Y translator assembly and the write and read probes maybe carried by the positionable support structure of the X translatorassembly. Moreover, the storage medium and the write and read probes maybe positioned with respect to each other with any of the alternativeembodiments described earlier for positioning device 100 or with astandard piezoelectric XY translator apparatus.

To write up to 33 data bits or data values at a time to storage medium202 during a write mode or cycle, write probes 204 can be arranged inthree rows of eleven, as shown in FIG. 9. As shown in FIG. 10, eachwrite probe includes a tapered write tip 210 and a Z translator or writetip positioning apparatus for positioning the write tip with respect tothe storage medium in the Z direction.

The Z translator apparatus comprises a cantilever 208 and a cantilevermover. The cantilever mover is a capacitor formed by moveable supportstructure 166, an insulating layer or pad 212, and a conductive layer orpad 214. The cantilever is integrally connected to the moveable supportstructure and the write tip is integrally connected to and on thecantilever.

Each write probe 204 has a core material 216 that comprises a conductiveor semiconductive material, such as silicon. The core material of eachwrite tip 210 is preferably coated with a highly obdurate coating 218,such as diamond, silicon carbide, or carbon nitride, which is capable ofdeforming storage medium 202 and is more obdurate than conductivesilicon, tungsten, aluminum, or gold used in conventional STM tips. Thisis to reduce frictional wear from long term use in deforming the storagemedium. The obdurate coating may have a thickness in the range ofapproximately 5 Angstroms to 1 micrometer.

In the case where obdurate coating 218 comprises diamond, write probes204 are first placed in a vacuum chamber containing carbon. A mask isplaced over each probe so that only tip 210 is exposed. At a pressure ofapproximately 1×10-7 to 1×10-11, the carbon is heated to a temperatureof approximately 2100 to 3000□ C. The carbon condenses on the surface ofcore material 216 to form seed sights. Alternatively, the seed sightsmay be formed by pushing or rubbing each write tip 210 on a surfacecontaining fine grain diamond (such as a lap or polycrystalline diamondcoated surface). Referring to FIG. 11, write probes 204 are then placedin a methane hydrogen atmosphere for chemical vapor deposition (CVD) ofdiamond on the surface of the core material. As a result of the seedsights, a polycrystaline diamond coating 212 is grown on the corematerial with the diamond crystals being grown normal to the surface ofthe core material. Growth of diamond crystals is further described inDeposition, Characterization, and Device Development in Diamond, SiliconCarbide, and Gallium Nitride Thin Films, by Robert F. Davis, Journal ofVacuum Science and Technology, volume A 11(4) (July/August 1993), whichis hereby explicitly incorporated by reference.

Moreover, during the deposition process, a bias voltage may be appliedto the core material. This voltage should be sufficient to create anelectrical field at the sharp end of the write tip large enough so thatthe diamond crystals grown at the sharp end of the write tip aresymmetrically aligned but small enough so that the diamond crystalsgrown below the sharp end of the write tip are not symmetricallyaligned. The advantage of this is to obtain a consistent orientation andtip behavior at the sharp end without sacrificing the durability andstability of the diamond coating below the sharp end.

Moreover, in the case where the obdurate coating 218 comprises siliconcarbide, the coating may be grown in the manner described in Deposition,Characterization, and Device Development in Diamond, Silicon Carbide,and Gallium Nitride Thin Films just referenced.

And, when the obdurate coating 218 comprises carbon nitride, the sameseeding processes as was just described for diamond growth may be used.Then, write probes 204 are placed in an atmosphere of monatomicnitrogen. The monatomic nitrogen is obtained by passing nitrogen gasthrough a hollow tungsten heater consisting of a hollow tungstenstructure through which an electric current is passed. The tungstenheater is maintained at a temperature of 2100 to 3000 □C. In oneembodiment, the tungsten heater also includes a quantity of carbonsufficient to combine chemically to form a carbon nitride layer on thecarbon seed sites at the cool surface (800 □C) of core material 216. Inanother embodiment, the process begins without introducing nitrogen gas.After a few atoms of carbon are deposited, the nitrogen gas isintroduced into the tungsten electrode and deposition and growth of thepolycrystalline carbon nitride coating is initiated.

The types of probes just described are even further described incopending U.S. patent application Ser. No. 08/281,883, entitled“Scanning probe Microscope Assembly and Method for makingSpectrophotometric, Near-Field, and Scanning Probe Measurements”, byVictor B. Kley, which is hereby explicitly incorporated by reference.

As alluded to earlier, each write probe 204 includes a Z translatorapparatus comprising cantilever 208 and a capacitor formed by moveablesupport structure 166, insulating layer 212, and conductive layer 214.The moveable support structure is made to be conductive orsemiconductive. In addition, the insulating layer may comprise silicondioxide and the conductive layer may comprise tungsten. Controller 102is electrically coupled to the moveable support structure and theconductive layer. By applying a suitably large voltage across them, thecontroller can control enough energy storage by the capacitor of the Ztranslator apparatus so as to electrostatically move cantilever 208 fromits normal undeflected position to a deflected position and raise writetip 210 in the Z direction away from storage medium 202. By applying noor a suitably small voltage across the moveable support structure andthe conductive layer, the controller can control release of energystorage by the capacitor of the Z translator apparatus so as to movecantilever 208 from its deflected position towards its normalundeflected position and lower write tip 210 in the Z direction towardthe storage medium.

Referring to FIG. 11, in an alternative embodiment, the Z translatorapparatus of each write probe 204 may comprise, in addition tocantilever 208, a heater element 220 as the cantilever mover instead ofthe capacitor of the positioning apparatus of FIG. 10. The heaterelement is located on the cantilever at the notch formed between thecantilever and moveable support structure 166. Controller 102 iselectrically coupled to the moveable support structure and the heaterelement. By applying a suitably large voltage across them, thecontroller can produce a current through the heater element to thermallyexpand the cantilever at the notch so as to move it from its normalundeflected position to a deflected position and lower write tip 210 inthe Z direction toward storage medium 202. And, by applying no or asuitably small voltage across moveable support structure and the heaterelement, the controller produces no current through the heater elementand the cantilever thermally contracts at the notch and returns from itsdeflected position to its normal undeflected position so as to raisewrite tip in the Z direction away from the storage medium.

Additionally, in still another embodiment, the Z translator apparatus ofeach write probe 204 may be a conventional piezoelectric translator. Inthis case, write tip 210 of each write probe is connected to thepiezoelectric translator and controller 102 is coupled to thepiezoelectric translator to expand and contract it so as to lower orraise the write tip in the Z direction.

Referring back to FIG. 9, storage medium 202 comprises a deformableconductive material which is capable of being deformed by the obduratecoatings of write tips 210. This material may comprise gold, silicon,carbon, aluminum, silver, or tin.

Furthermore, still referring to FIG. 9, in a write mode, controller 102first controls the XY translator apparatus in positioning the writeprobes over an area or region of storage medium 202 to be written. Sincecontroller 102 is separately electrically coupled to the Z translatorapparatus of each write probe 204 in the manner described earlier, itcan selectively or individually control the lowering of each write tip210 in the Z direction to write individual data bits or data values tostorage medium 202 during the write mode. Specifically, during the writemode, each write tip may be selectively and individually lowered aselected predetermined amount into the storage medium in the manner justdescribed to cause a selected predetermined amount of deformation orindentation in the storage medium which represents digital or analogdata. In an embodiment for writing binary bits of digital data with eachwrite tip, a data bit of value “1” and a data bit of value “0” arerepresented by two different predetermined amounts of deformation of thestorage medium. Thus, for example, a data bit of value “0” may berepresented by no deformation and a data bit of value “1” may berepresented by a specific amount of deformation. However, in anembodiment for writing a larger range of digital data values or analogdata values with each write tip, a range of discrete predeterminedamounts of deformation would represent a range of digital data valuesand a continuous range of predetermined amounts of deformation wouldrepresent a range of analog data values. Thus, for example, in eithercase the range of predetermined amounts of deformation may range from nodeformation representing a minimum data value to a maximum amount ofdeformation representing a maximum data value.

The write operation just described is similarly described in U.S. Pat.No. 5,038,322 referred to earlier and hereby explicitly incorporated byreference. Moreover, since in the embodiment of FIG. 9 there are 33write probes 204, up to 33 data bits or data values at a time may bewritten to storage medium 202 during a write mode in this manner.

In order that the data written to storage medium 202 may be properlyread, a pattern of tracks at regularly spaced intervals are formed onthe storage medium. These tracks may be created using conventionalphotolithography during the microfabrication process. Alternatively,they may be a series of deformations created in the storage medium withwrite tips 210 in the manner described earlier. These tracks may be readout as data bits or data values along with the actual data bits or datavalues written to storage medium in the manner described next.

Referring to FIG. 9, to read up to 33 data bits or data values at a timefrom storage medium 202 during a read mode, read probes 206 may bearranged in three rows of eleven. And, referring to FIG. 12, each readprobe includes a tapered read tip 222 and a Z translator or read tippositioning apparatus for positioning the read tip in the Z direction.

The Z translator apparatus is constructed and operates like the Ztranslator apparatus of each write probe and therefore comprises acantilever 208 and a capacitor formed by moveable support structure 166,an insulating layer 212, and a conductive layer 214. The cantilever isintegrally connected to the moveable support structure and the read tipis integrally connected to and on the cantilever. Alternatively, the Ztranslator apparatus of each read probe 206 may comprise one of theapparatuses discussed earlier as alternative embodiments to the Ztranslator apparatus of each write probe 204. Thus, each read tip may beselectively and individually lowered toward or raised away from thestorage medium in the Z direction in a similar manner to that describedearlier for each write tip 210.

Referring to FIG. 12, like each write probe 204, each read probe 206 hasa core material 216 that comprises a conductive or semiconductivematerial, such as silicon. The core material of each read tip 222 iscoated with an insulating coating 226, such as silicon dioxide, exceptat the sharp end of the read tip. The insulating coating and the corematerial at the sharp end of the tip are coated with a conductivecoating 228, such as aluminum, gold, tungsten, or some other conductivematerial. To operate each read tip as an STM tip, controller 102 iselectrically coupled to the conductive coating of the read tip.

Referring to FIG. 9, in a read mode, controller 102 first controls theXY translator apparatus in positioning the read probes over an area orregion of storage medium 202 to be read. Since controller 102 isseparately electrically coupled to the Z translator apparatus of eachread probe 206, it can selectively and individually control the loweringof each read tip 222 in the Z direction close to the storage medium forreading data from the storage medium during the read mode. Moreover,since the controller is electrically coupled to storage medium 202 andseparately coupled to conductive coating 228 of each read tip, it canselectively and individually produce and measure a tunneling currentbetween the conductive coating of each read tip and the storage mediumduring the read mode. From the measured tunneling current, thecontroller determines the amount of deformation of the storage mediumbelow the read tip so as to read a data bit or data value from thestorage medium which was written during a previous write mode.

Furthermore, the read operation just described is similarly described inU.S. Pat. No. 5,038,322 referred to earlier and in U.S. Pat. Nos.5,289,408 and 5,317,533 also referred to earlier and hereby explicitlyincorporated by reference. Furthermore, since there are 33 read probes206 in the embodiment of FIG. 9, up to 33 data bits or data values at atime may be read from storage medium 202 during a read mode in thismanner.

In the embodiment of FIG. 9, each row of write and read probes 204 and206 are spaced about 30 micrometers apart and the write and read probesin each row are also spaced about 30 micrometers apart. This is done tomatch the ranges of movement of the moveable support structures of X andY translator assemblies 104 and 106 so as to maximize the amount of datathat can be written to and read from storage medium 202 at nanometerlevel positioning increments over these ranges of movement.

Additionally, to enable data bits or data values written to storagemedium to be erased, the deformable material of the storage medium 202is capable of being heated to or near its melting point. As a result, inthe area where the storage medium is being heated, it will be restoredto its normal state and any deformations there representing data bits ordata values will be removed.

In an erase mode, controller 102 controls the XY translator apparatus inpositioning the read probes over an area or region of storage medium 202to be erased. As indicated earlier, controller 102 is separatelyelectrically coupled to the Z translator apparatus of each read probe206 and can selectively and individually control the lowering of eachread tip 222 in the Z direction close to the storage medium for erasingof data from the storage medium during the erase mode. Additionally,referring to FIG. 12, to also enable the erasing of data written to thestorage medium, the controller is electrically coupled to core material216 of each read probe 206 in that moveable support structure 166 andread probe 206 are integrally connected and comprise a conductive orsemiconductive material.

Since the controller is separately electrically coupled to theconductive coating of each read tip, as discussed earlier, and iscoupled to the core material 216 of each read tip, it can selectivelyand individually apply a voltage across the conductive coating and corematerial of each read tip during the erase mode. At the sharp end ofeach read tip 222, the conductive coating is in contact with the corematerial and a current is produced between them when the applied voltageacross them reaches the forward bias point of the junction diode theyform. Since the read tip has been lowered close to the storage mediumduring the erase mode, the heat generated by this flow of currentradiates down toward storage medium 202 to heat the area of the storagemedium below the read tip. This restores the storage medium in this areato its natural state and removes any deformation there so that a databit or data value written to the storage medium during a previous writemode and represented by the deformation can be selectively andindividually erased by the controller. Since there are 33 read probes206 in the embodiment of FIG. 9, up to 33 data bits or data values at atime may be erased from storage medium 202 during an erase mode in themanner just described.

In an alternative embodiment, each read probe 206 would not have its ownZ translator apparatus. Instead, each read probe would be connected to alarge single Z translator apparatus which would be controlled bycontroller 102 to lower read tips 222 simultaneously together to performin bulk the read and erase functions described earlier.

Turning to FIG. 13, data bits or data values written to storage medium202 may be erased in another way. In this embodiment, the storage mediumcomprises a layer of a deformable material 229, as described earlier,and a heater structure comprising a first insulating layer 230, one ormore patterned conductive heater elements 232 over the first insulatinglayer, and a second insulating layer 234 over the first insulating layerand heater elements and below the deformable material.

FIG. 14 shows the patterned layout of heater elements 232. Controller102 is separately electrically coupled across each heater element toselectively and individually apply across the heater element a voltageto heat the area (i.e., region) of storage medium 202 above the heaterelement. In doing so, controller 102 can selectively remove deformationsin particular areas of the storage medium in a similar manner to thatjust described and therefore selectively erase data bits or data valueswritten to these areas.

Turning again to FIG. 12, in an alternative embodiment, conductivecoating 228 comprises an obdurate material, such as diamond, siliconcarbide, or silicon nitride, made to be conductive using conventionaldoping techniques. For example, these materials may be doped with boronto make them conductive. In this embodiment, probes 206 could then beused not only to read data from storage medium 202 in the mannerdescribed earlier, but also write data to storage medium 202 in themanner described for write probes 204 of FIG. 10. Thus, only one kind ofprobe could be used in this embodiment to perform reading and writing ofdata to and from the storage medium.

Still referring to FIG. 12, in still another embodiment, the corematerial of read tips 222 would be conductive so that these tips wouldnot require conductive coating 228 and insulating coating 226. In thiscase, the core material may comprise doped silicon, tungsten, aluminum,gold, or some other conductive material.

OPTICAL WRITE/ELECTRICAL READ EMBODIMENT

Referring to FIGS. 15 and 16, in another embodiment of data storagedevice 200, storage medium 202 comprises optically alterable chargestorage cells, regions, or areas of the type used in UV erasableprogrammable read only memories (UVPROMs). However, in this case, thesecharge storage cells do not have individual read/write lines. To providethe charge storage cells, the storage medium comprises a siliconsubstrate 236 in which are formed electrically isolated, spaced apart,and conductively doped wells 238 capable of storing a charge. Controller102 is electrically coupled to the substrate so that it is electricallycoupled to each doped well that forms the charge storage cells.

Moreover, referring to FIG. 9, write probes 204 of the read/writemechanism are constructed to optically write data to the charge storagecells of storage medium 202 while read probes 206 are constructed toelectrically read the data optically written to the charge storagecells. Otherwise, the data storage device in this embodiment isconstructed and operates the same as the one of the mechanicalwrite/electrical read embodiment discussed earlier.

FIG. 17 shows the construction of each write probe 204 of thisembodiment. Like the write probes of the embodiment of FIG. 10, eachwrite probe has a conductive or semiconductive core material 216, suchas silicon. The core material of each write tip 242 is coated with anemissive coating 244 at a thickness of approximately 10 to 200nanometers. This emissive coating may comprise gallium nitride, galliumarsenide, or silicon carbide all suitably doped to be emissive. Aconductive coating 246, such as aluminum, gold, tungsten, indium tinoxide, or some other conductive material, is over the emissive coatingand has a thickness of approximately 20 to 200 nanometers. About 5 to 10nanometers of the conductive coating at the sharp end may be madesufficiently thin so that it is transparent to blue and/or UV light orabout 5 to 10 nanometers of the conductive coating can removed or rubbedoff from the sharp end of the write tip. This forms an aperture at thesharp end of the tip with a diameter in the range of approximately 5 to100 nanometers. With a voltage of about 4 volts applied across theconductive coating and core material, blue (e.g., 423 nanometerwavelength) and/or ultraviolet (UV) light (e.g., 372 nanometerwavelength) is emitted by emissive coating 240 as described inDeposition, Characterization, and Device Development in Diamond, SiliconCarbide, and Gallium Nitride Thin Films referenced earlier. The lightpropagates through the write tip until it is emitted at its sharp end atthe aperture which has a diameter substantially smaller than thewavelength of the light. This type of probe is even further described inthe copending U.S. patent application Ser. No. 08/281,883 referencedearlier.

In an alternative embodiment shown in FIG. 18, each write probe 204 iscomprised of a silicon core material 216. The silicon core material atthe sharp end of each write tip 248 is porous. This is accomplished byimmersing the write probe in a dilute solution of Hydrofluoric acid or adilute solution Hydrofluoric and Nitric acid and operating the siliconwrite probe as an anode. In addition, a gold or platinum cathode is alsoimmersed in the solution. A current is then produced between the anodeand cathode which is sufficient to porously etch the sharp end of thewrite tip (and other sharp edges of the write probe) but leave theremainder of the write probe unetched. The silicon core material of eachwrite tip is coated with an insulating coating 250, such as silicondioxide, except at the sharp end of the read tip. The insulating coatingand the porous core material at the sharp end of the tip are coated witha conductive coating 252, such as aluminum, gold, tungsten, indium tinoxid, or some other conductive material. To form an aperture at thesharp end of the tip, about 5 to 10 nanometers of the conductive coatingat the sharp end may be made sufficiently thin so that it is transparentto light or about 5 to 10 nanometers of the conductive coating canremoved or rubbed off from the sharp end of the write tip.

Controller 102 is electrically coupled to core material 216 of eachwrite probe 248 in that moveable support structure 166 and write probe248 are integrally connected and comprise silicon. Moreover, thecontroller is separately electrically coupled to conductive coating 252of each write tip 248. Thus, the controller can selectively andindividually apply a voltage across the conductive coating and corematerial of each read tip. Since at the sharp end of each write tip theconductive coating is in contact with the porous core material, acurrent can is produced between them when the voltage is applied whichcauses the porous core material at the sharp end to emit light throughthe aperture of the write tip.

Alternatively, write tip 248 may be uncoated. In this embodiment,controller 102 may be electrically coupled across core material 216 ofeach write tip and substrate 230 of storage medium 202. By selectivelyand individually applying a voltage across them, a current will beproduced between the charge storage cell close to the write tip and thewrite tip which causes the porous core material at the sharp end of thewrite tip to emit light.

Light emission by porous silicon is further described in An ImprovedFabrication Technique for Porous Silicon, Review of ScientificInstruments, v64, m2 507-509 (1993), Photoluminescence Properties ofPorous Silicon Prepared by Electrochemical Etching of Si EpitaxialLayer, Act. Physics Polonica A, v89, n4, 713-716 (1993), Effects ofElectrochemical Treatments on the Photoluminescence from Porous Silicon,Journal of the Electrochemical Society, v139, n9, L86-L88 (1992),Influence of the Formation Conditions on the Microstructure of PorousSilicon Layers studied by Spectroscopic Ellipsometry, Thin Solid Films,v255, n1-2; 5-8 (1995), and Formation Mechanism of Porous Si LayersObtained by Anodization of Mono-Crystalline N-type Si in HF Solution andPhotovoltaic Response in Electrochemically Prepared Porous Si, SolarEnergy Materials and Solar Cells, v26, n4, 277-283. which are herebyexplicitly incorporated by reference.

Furthermore, referring to FIG. 9, in a write mode, controller 102 firstcontrols the XY translator apparatus in positioning write probes 204over charge storage cells to be written. As discussed earlier,controller 102 is separately electrically coupled to the Z translatorapparatus of each write probe 204 and can selectively control thelowering of each write tip 242 in the Z direction to write data to acharge cell during the write mode. Moreover, as shown in FIGS. 17 and18, controller 102 is separately electrically coupled to each writeprobe to make it emit light. Thus, during a write mode, the controllercan selectively and individually control each write tip to write a databit or data value to a charge storage cell by emitting a selectedpredetermined amount of light close to a charge cell in the manner justdescribed to cause a selected predetermined amount of charge in thecharge storage cell to be optically leaked off, altered, or changed sothat the charge storage cell stores a selected predetermined amount ofcharge representing the data bit or data value.

Specifically, in an embodiment for writing binary bits of digital datawith each write tip, a data bit of value “1” and a data bit of value “0”are represented by two different predetermined amounts of charge in acharge cell. Thus, for example, a data bit of value “0” may berepresented by a specific charge amount that has been optically changedand a data bit of value “1” may be represented by a specific chargeamount that has not been optically changed. However, in an embodimentfor writing a larger range of digital data values with each write tip, arange of predetermined charge amounts represent a range of digital datavalues. Thus, for example, the range of predetermined charge amounts mayrange from no charge representing a minimum data value to a maximumamount of charge representing a maximum data value. Since there are 33write probes, up to 33 data bits or data values can be written to up to33 charge storage cells during a write mode in the manner justdescribed.

Referring to FIG. 12, read probes 206 in this embodiment may beconstructed in the same way as those of the mechanical write/electricalread embodiment described earlier. Thus, in a read mode, controller 102controls the XY translator apparatus in positioning the read probes overcharge storage cells to be read. And, as described earlier, controller102 is separately electrically coupled to the Z translator apparatus ofeach read probe 206 and can individually and selectively control thelowering of each read tip 222 in the Z direction to detect with theconductive coating of the read tip a charge in a charge storage cell ofstorage medium 202. Moreover, since the controller is also separatelycoupled to conductive coating 228 of each read tip, it can individuallyand selectively measure the amount of the detected charge so as to reada data bit or data value from the charge storage cell which was writtenduring a previous write mode. In other words, the read tip is used todetect the predetermined amount of alteration of the charge storage cellcaused during a write mode and the controller measures the detectedamount to read the data bit or data value written during the write mode.Since there are 33 read probes, up to 33 data bits or data values at atime during a read mode can be read in this manner from up to 33 chargestorage cells.

Furthermore, referring to FIGS. 15 and 16, as indicated previously thecharge storage cells are of the type found in UVPROMs. However,read/write lines are eliminated such that the charge storage cells maybe made much smaller and spaced much closer than in conventionalUVPROMs. As a result, in this embodiment, the size of the charge storagecells may be on the nanometer level and the charge storage cells may bespaced apart at nanometer level increments. This is so that data can bewritten to and read from storage medium 202 at nanometer levelincrements of positioning using X and Y translator assemblies 104 and106 of FIGS. 1 and 9 in the manner described earlier.

Additionally, the typical standard energy from common UV sources used toerase UVPROMs is on the order of 10-9 watts per micrometer. However,light emitting tips 242 and 248 described herein will easily produce UVenergy at a near-field intensity of 107 to 108 times more intense whichresults in write times on the order of 1 to 10 microseconds.

Furthermore, during an erase mode, controller 102 controls the XYtranslator apparatus in positioning read probes 206 over charge storagecells to be erased. Since controller 102 is separately electricallycoupled to the Z translator apparatus of each read probe 206, it canindividually and selectively control the lowering of each read tip 222in the Z direction close to storage medium 202 for erasing of data froma charge storage cell during the erase mode. Moreover, referring toFIGS. 12 and 16, as discussed earlier, the controller is separatelyelectrically coupled to conductive coating 228 of each read tip and iselectrically coupled to substrate 236 of the storage medium. Thus, itcan individually and selectively apply a selected predetermined voltageacross the conductive coating of each tip and the charge storage cellunder the tip during the erase mode. Since the read tip is lowered closeto the charge storage cell during the erase mode, this results in aselected predetermined amount of tunneling current being producedbetween the conductive coating and the charge storage cell so that aselected predetermined amount of charge is injected or transferred intothe charge storage cell. Thus, the charge in the charge storage cell isrestored to this predetermined amount so that it can be changed in asubsequent write mode when again writing a data bit or data value to thecharge storage cell. Since there are 33 read probes 204, up to 33 databits or data values may be erased at a time during an erase mode from upto 33 charge storage cells in the manner just described.

Referring to FIGS. 15 and 16, data bits or data values written to thecharge storage cells of storage medium 262 may also be eased in anotherway. Specifically, the storage medium also includes an insulating layer254 around doped wells 238. Over the insulating layer are one or morepatterned conductors 256 around one or more corresponding areas orregions of the doped wells.

Controller 102 is separately electrically coupled across each conductorand the silicon substrate to selectively and individually apply acrossthem a predetermined voltage. This produces a selected predeterminedamount of tunneling current between the conductor and the charge storagecells in the corresponding selected region and injects a selectedpredetermined amount of charge into these charge storage cells. As aresult, any data bits or data values written to these charge storagecells during a previous write mode are erased in a similar manner tothat just described.

In alternative embodiments, the storage medium may comprise other typesof materials or structures which can be optically altered at discreteincrements, regions, or intervals by light emissions from the types ofwrite probes 204 discussed next.

In an additional alternative embodiment, each write and read probe 204and 206 would not have its own Z translator apparatus. Instead, eachwrite probe would be connected to a large single Z translator apparatuswhich would be controlled by controller 102 to lower write tips 242 or248 simultaneously together to perform in bulk the write functiondescribed earlier. Moreover, each read probe would also be connected toa large single Z translator apparatus which would be controlled bycontroller 102 to lower read tips 222 simultaneously together to performin bulk the read and erase functions described earlier.

Referring to FIGS. 9 and 18, in still another alternative embodiment,instead of being used as a data storage device, device 200 could be usedas a biochemical instrument. In this case, the biochemical instrumentincludes one or more probes 204 each having a tip 248 with a poroussharp end, as described earlier, but without insulating and conductivecoatings 250 and 252. Specifically, by controlling the etch current andetch time of the process described above, the pore width and depth of aregion of several angstroms in length at the sharp end of the tip can becontrolled. As a result, binding cites of a specific size for selectedmolecules can be made in the tip at the sharp end so that controller 102could control the lowering and raising of the tip, in the mannerdescribed earlier, into and from a biochemical substance tobiochemically interact with it.

For example, a tip of this embodiment which holds specific types ofmolecules in its binding cites could be lowered into and out of an assayfor viruses or other bioactive chemicals or biostructures to depositthem into or remove them from the assay. Similarly, a tip that holds inits binding cites the molecules of a catalytic chemical may be loweredinto a substance to produce a catalytic reaction in the substance. Or,the tip may be lowered into and raised from a biochemical substance,such as a cell, to attract and pick up specific molecules at the bindingcites of the tip. Additionally, the binding sites may hold the moleculesof a chemically active material so that when the tip is lowered into anunknown sample of organic or inorganic material, the binding energy orattractive force between the molecules of the chemically active andsample materials can be measured by the deflection of cantilever 208 tocharacterize the sample material. In this case, the deflection of thecantilever would be determined by the controller by measuring changes inthe energy storage of the capacitor described earlier (formed by themoveable support structure 166, insulating layer 212, and conductivelayer 214) or with a laser and photodetector assembly like in aconventional AFM and described further in the copending U.S. patentapplication Ser. No. 08/281,883 referenced earlier.

ELECTRICAL WRITE/READ EMBODIMENT

Referring to FIGS. 15 and 16, in another embodiment of data storagedevice 200, storage medium 202 comprises charge storage cells, regions,or areas similar to the UVPROM type charge storage cells of the opticalwrite/electrical read embodiment described earlier and of the type usedin electronically erasable programmable read only memories (EEPROMs).However, like the UVPROM type charge storage cells, they do not haveread/write lines and are constructed similar to the UVPROM type storagecells.

Referring to FIG. 12, in this embodiment, data storage device uses onlyprobes 206 of the type described in the mechanical write/electrical readembodiment. These probes are used to electrically read and erase datafrom the charge storage cells in a similar manner to that discussedearlier. Moreover, they are also used to electrically write data to thecharge storage cells which is done in a similar fashion to the way inwhich data is erased from the charge storage cells. However, in thiscase, a predetermined amount of charge of opposite polarity to thecharge injected during an erase mode is injected into a charge storagecell to change the charge stored by the charge storage cell and write toit a data bit or data value. In other words, In other words, the chargestorage cell is electrically altered by a predetermined amount to writedata to it. Otherwise, this write operation is the same as the eraseoperation discussed earlier and is further described in U.S. Pat. Nos.5,289,408 and 5,317,533.

Furthermore, like the UVPROM type storage cells discussed earlier, thesize of the EEPROM type charge storage cells may be at the nanometerlevel and they may be spaced apart at nanometer level increments sincethey do not require address lines and read/write lines. Thus, in thisembodiment as well, data can be written to and read from storage medium202 at nanometer level increments of positioning using X and Ytranslator assemblies 104 and 106 of FIGS. 1 and 9 in the mannerdescribed earlier.

In alternative embodiments, the storage medium may comprise other typesof materials or structures which can be electrically altered at discreteincrements, regions, or intervals by tunneling currents from the typesof probes 206 discussed next. These types of materials or structures mayinclude magnetic materials or the types of materials and structures asdescribed in U.S. Pat. Nos. 5,289,408 and 5,317,533 referred to earlier.

ACOUSTICALLY AIDED ELECTRICAL WRITE/READ EMBODIMENT

Referring to FIGS. 15 and 16, in another embodiment of data storagedevice 200, storage medium 202 also comprises the EEPROM type chargestorage cells described earlier for the electrical write/readembodiment. Furthermore, referring to FIGS. 19 and 20, in thisembodiment, the write and read probes 204 and 206 described earlier arereplaced by a write/read mechanism that operates similarly to the probes206 of the electrical write/read embodiment but is acoustically aided.The acoustically aided electrical write/read mechanism comprises a ridgesupport structure 254, one or more parallel triangular ridges 256integrally connected to the base support structure, and an acoustic wavegenerator on the ridge support structure comprising two interleavedpiezoelectric transducers or actuators 258. The storage medium andacoustically aided electrical write/read mechanism can be positionedwith respect to each other in the ways described earlier.

Triangular ridges 256 extend down from the flat lower surface of ridgesupport structure 254. The triangular ridges are constructed similarlyto tips 222 of FIG. 12 in that each has a conductive or semiconductivecore material, such as silicon, integrally connected to the ridgesupport structure, an insulating coating over the core material exceptat the sharp end of the ridge, and a conductive coating over theinsulating coating and the core material at the sharp end. Moreover,controller 102 is also separately electrically coupled to the conductivecoating of each of the triangular ridges.

Referring back to FIGS. 19 and 20, piezoelectric transducers 258 of theacoustic wave generator are positioned on the flat upper surface ofridge support structure 254 so as to generate surface acoustic waves 255that propagate on the upper surface in the X direction and parallel tothe axial length of the triangular ridges in the Y direction. Controller102 is electrically coupled to the piezoelectric transducers to generatea surface acoustic wave during each write, read, and erase mode.

During a write mode, controller 102 first controls the XY translatorapparatus in positioning triangular ridges 258 over corresponding chargestorage cells to be written. Then, the controller controls the acousticwave generator in generating an acoustic wave that propagates on thesurface of the ridge support structure parallel to the axial lengths ofthe triangular ridges. To write a data bit or data value to a particularcharge storage cell under each triangular ridge, controller 102selectively and individually applies a write voltage pulse of a selectedpredetermined voltage across the conductive coating of the triangularridge and the substrate of storage medium 202 at a selectedpredetermined time and for a selected predetermined time interval orduration during the propagation of the acoustic wave. The predeterminedtime corresponds to the location of the charge storage cell because atthis predetermined time the portion of the ridge support structure overthe charge storage cell is displaced by the propagating surface acousticwave down toward the charge storage cell so that the portion of thetriangular ridge connected to this portion of the ridge supportstructure is also displaced down toward the charge storage cell. As aresult, the predetermined voltage of the write voltage pulse over thepredetermined time interval produces a selected predetermined amount oftunneling current between the conductive coating of the triangular ridgeand the charge storage cell. Thus, a charge of a selected predeterminedamount is injected into the charge storage cell so that a data bit ordata value is written to it in a similar manner to that describedearlier in the electrical write/read embodiment. In other words, thecharge storage cell is electrically altered by a predetermined amount.

For example, the speed of a surface acoustic wave in ridge supportstructure 254 may be about 1000 meters/sec (typical for semiconductivematerials). Thus, if the storage medium includes 1000 charge storagecells under a triangular ridge over a 1 millimeter distance along thepropagation direction of an acoustic wave, then the acoustic wave wouldtraverse each charge storage cell in 1 nanosecond. In order to write adata bit or data value to the 500th charge storage cell under aparticular triangular ridge, a write voltage pulse would be appliedacross the conductive coating of the triangular ridge and the substrateof the storage medium for a 1 nanosecond time interval 500 nanosecondsafter the wave front of the acoustic wave first begins propagating overthe triangular ridge. Since there are 8 triangular ridges in theembodiment of FIGS. 19 and 20, up to 8 data bits or data values can bewritten at a time during a write mode to up to 8 charge storage cells inthe manner just described.

Similarly, in a read mode, controller 102 controls positioning oftriangular ridges 258 over corresponding charge storage cells to be readand controls the acoustic wave generator in generating an acoustic wave.Controller 102 then measures the amount of the charge detected by theconductive coating of each triangular ridge at a selected predeterminedtime and for a selected predetermined time interval during thepropagation of the acoustic wave. As in the write mode, thepredetermined time corresponds to the location of the charge storagecell so that at this predetermined time the triangular ridge isdisplaced down toward the charge storage cell in the manner describedearlier and the conductive coating of the triangular ridge detects thecharge of the charge storage cell. As a result, a data bit or data valueis read from the charge storage cell in a similar manner to thatdescribed earlier in the optical write/electrical read and electricalwrite/read embodiments. In other words, the triangular ridge is used todetect the predetermined amount of electrical alteration of the chargestorage cell during a write mode and the controller measures thedetected amount to read the data bit or data value written during thewrite mode. Up to 8 data bits or data values can be read at a timeduring a read mode from up to 8 charge storage cells in the manner justdescribed since there are 8 triangular ridges in the embodiment of FIGS.19 and 20.

Additionally, in an erase mode, data bits or data values are erased in asimilar fashion to which they are written. However, during the erasemode, a predetermined amount of charge of opposite polarity to thecharge injected during an erase mode is injected into a charge storagecell to change the charge stored by the charge storage cell and erase adata bit or data value written during an earlier write mode.

Controller 102 adjusts the timing and duration of the write and erasevoltage pulses during write and erase modes and the timing and durationof the charge detection during a read mode to corresponding to changesin temperature. As a result, the position in the storage medium overwhich a read or write is done always remains constant regardless oftemperature change.

Furthermore, bulk erasing may also be performed in the same manner asdescribed earlier in the optical write/electrical read and electricalwrite/read embodiments.

In an alternative embodiment, the acoustic wave generator may bepositioned instead on the upper surface of storage medium 202. As in theembodiment where it is positioned on ridge support structure 254, itwould be positioned so that the acoustic waves it generates propagate ina direction parallel to the axial length of triangular ridges 256. As aresult, the charge storage cells would be displaced rather than thetriangular ridges in positioning the triangular ridges close to thecharge storage cells to write, read, and erase data in the waysdescribed earlier.

In other alternative embodiments, the core material of triangular ridges256 would be conductive so that these tips would not require aconductive coating and an insulating coating. In this case, the corematerial may comprise doped silicon, tungsten, aluminum, gold, or someother conductive material. Moreover, the storage medium could comprisean electronically alterable material or structure of the type alsodescribed in the electrical write/read embodiment.

Similar to the read and write probes 204 and 206 of the earlierdiscussed embodiments, triangular ridges 256 could be spaced about 30micrometers apart. Referring to FIG. 9, this is done to match the rangeof movement of the moveable support structure of Y translator assembly106 so as to maximize the amount of data that can be written to and readfrom storage medium 202 at nanometer level positioning increments overthis range of movement.

Finally, positioning of storage medium 202 and the acoustically aidedelectrical write/read mechanism could be alternatively accomplished asshown in FIGS. 21 and 22. In this case, a Y translator apparatus thatcomprises a stationary support structure 260, a pair of thermallyexpandable and contractible structures 262, and heater elements 264 isused to position the triangular ridges over charge storage cells in theY direction (i.e., orthogonal to the direction of propagation of thesurface acoustic waves generated by the acoustic wave generator).

In this embodiment, storage medium 202 is fixedly coupled to stationarysupport structure 260 and ridge support structure 254 has vertical endportions that rest on but are not directly connected to the stationarysupport structure. Each of the end portions is integrally connected to acorresponding thermally expandable and contractible structure 262. Thethermally expandable and contractible structures are both integrallyconnected to the stationary support structure. Heater elements 264 arelocated at the elbows of the thermally expandable and contractiblestructures and are used to selectively heat the thermally expandable andcontractible structures so that they thermally expand and contract andmove back and forth in the Y direction. Thus, the thermally expandableand contractible structures movably couple the stationary supportstructure to the ridge support structure in a way similar to thatdescribed earlier in which thermally expandable and contractiblestructure 132 movably couples the stationary support structure and themoveable support structure of the X translator assembly 104 of FIG. 2.

Furthermore, in this embodiment, to control the heater drive justdescribed, controller 102 is electrically coupled to heater elements 264and thermally expandable and contractible structures 262 to provide acurrent that flows through the heater elements. By controlling theamount of current that flows through the heater elements, the controllercan control positioning of ridge support structure 254 in nanometerlevel increments in the Y direction in a similar manner to thatdescribed earlier for the embodiment of FIG. 1.

Alternatively, the vertical end portions of ridge support structure 254could be fixedly coupled to stationary support structure 260. In thiscase, storage medium 202 would be movably coupled to the stationarysupport structure 260 by thermally expandable and contractiblestructures like those just discussed and positioning of the storagemedium in the Y direction would be accomplished similarly to that justdiscussed.

Furthermore, in still other embodiments, piezoelectric transducers, likethose discussed for X translator assembly 104 of FIG. 3, could be usedin place of the thermally expandable and contractible structures andheater elements in the embodiments just discussed. Their movement wouldbe accomplished in a similar way to that discussed for the X translatorassembly of FIG. 3.

CONCLUSION

While the present invention has been described with reference to a fewspecific embodiments, the description is illustrative of the inventionand is not to be construed as limiting the invention. Furthermore,various other modifications may occur to those skilled in the artwithout departing from the true spirit and scope of the invention asdefined by the appended claims.

1. A data storage device comprising: a deformable storage medium adaptedto store data in the form of one or more indentations mechanicallyimpressed thereon; a plurality of heat probes for supplying heat to thedeformable storage medium; a probe positioning apparatus to position theplurality of heat probes with respect to the storage medium; and acontroller configured to (A) during an erase mode, control the probepositioning apparatus in positioning a given one of the heat probesproximate a first of the one or more indentations, and (B) during theerase mode, cause the given one of the heat probes to heat the storagemedium to or near its melting point so that the first indentation in thestorage medium is removed and the data is erased.
 2. The data storagedevice of claim 1 in which the storage components are operated in avacuum.
 3. The data storage device of claim 1 in which the storagecomponents are operated in an inert gas.
 4. A data storage device foruse with a deformable storage medium having stored data in the form ofone or more indentations mechanically impressed thereon, the datastorage device comprising: a plurality of heat probes for supplying heatto the deformable storage medium; a probe positioning apparatus toposition the plurality of heat probes with respect to the storagemedium; and a controller configured to (A) during an erase mode, controlthe probe positioning apparatus in positioning a given one of the heatprobes proximate a first of the one or more indentations, and (B) duringthe erase mode, cause the given one of the heat probes to heat thestorage medium to or near its melting point so that the firstindentation in the storage medium is removed and the data is erased. 5.The data storage device of claim 4 in which the storage components areoperated in a vacuum.
 6. The data storage device of claim 4 in which thestorage components are operated in an inert gas.
 7. A data storagedevice comprising: a deformable storage medium; a plurality of probeseach comprising: a tip comprising a conductive highly obdurate coatingcapable of deforming the storage medium, and a tip positioning apparatusto lower the tip; a plurality of heat probes for supplying heat to thedeformable medium; and a probe and storage medium positioning apparatusto position the probes over the storage medium; and a controller to (A)during a write mode, control the probe and storage medium positioningapparatus in positioning the probes over the storage medium, (B) duringthe write mode, control each tip positioning apparatus in lowering thecorresponding tip a predetermined amount into the storage medium so asto cause a predetermined amount of mechanical deformation in the storagemedium representing data written thereto, (C) during read mode, controlthe probe and storage medium positioning apparatus in positioning theprobes over the storage medium, (D) during the read mode, control eachtip positioning apparatus in lowering the corresponding tip close to thestorage medium, and (L) during the read mode, produce and measure atunneling current between the conductive obdurate coating of each tipand the storage medium to identify a predetermined amount of deformationcaused in the storage medium below the corresponding tip during thewrite mode so that the data written thereto is read therefrom, and (F)during an erase mode, control the positioning apparatus in positioning agiven one of the heat probes proximate a first of the one or moreindentations, and (G) during the erase mode, cause the given one of theheat probes to heat the storage medium to or near its melting point sothat the first indentation in the storage medium is removed and the datais erased.
 8. The data storage device of claim 7 wherein the pluralityof heat probes use the same tips as the plurality of probes.
 9. The datastorage device of claim 7 wherein the plurality of heat probes usedifferent tips than the plurality of probes.
 10. The data storage deviceof claim 7 in which the storage components are operated in a vacuum. 11.The data storage device of claim 7 in which thestorage components areoperated in an inert gas.